Accounting for Climate in Ranking Countries’ Carbon Dioxide Emissions

Increased concern about carbon dioxide emissions has resulted in efforts to create methods for ranking countries according to their emissions. Such rankings inform policy decisions on an international scale; the more comprehensive these rankings are, the better our chances of reducing emissions. It has long been recognized that comparing individual countries based on their absolute amounts of carbon dioxide emissions is problematic. So it is common to adjust the total amount of emissions in order to account for the size of each country’s population and its overall economic output. These adjustments result in measures such as emissions per capita and emissions per gross domestic product (GDP).

We feel it is important to go a step further, taking into account another factor: the general heating and cooling demands that are imposed by the climate of a given country. The population of a country cannot choose the local climate, of course; that is determined by geographical location. Thus, people must deal with the temperature of their locale using the heating and cooling methods available to them. There are significant incentives for doing so: Effective indoor climate control results not only in increased comfort, but also in improved health and increased productivity. Consequently, in evaluating countries’ carbon dioxide emissions, we should not overlook climate.

One approach for incorporating climate into emissions rankings would involve subtracting emissions caused by heating and cooling from total emissions. However, a variety of technologies provide heating and cooling, resulting in widely varying amounts of carbon dioxide emissions per degree of change in indoor temperature. Even if information about emissions from indoor temperature regulation were available for each country (which it is not), this approach would not reward countries that rely primarily on carbon-efficient methods of climate control, nor would it penalize countries that rely on carbon-inefficient methods. Thus, an alternate approach is necessary.